Skip to Main content Skip to Navigation
Journal articles

Silica-Supported Tungsten Neosilyl Oxo Precatalysts: Impact of the Podality on Activity and Stability in Olefin Metathesis

Abstract : In order to establish structure–reactivity relationships in propylene metathesis as a function of the podality of tungsten oxo species bearing neosilyl ligands, we targeted the parent tris alkyl [(≡SiO)WOR3] and bis alkyl oxo [(≡SiO)2WOR2] derivatives prone to carbene formation. Thus, [WO(CH2SiMe3)3Cl] (1) was grafted onto silica dehydroxylated at 700 °C (SiO2–700), proceeding via W–Cl cleavage to yield well-defined monopodal species [(≡SiO)WO(CH2SiMe3)3] (2a) along with HCl release. On the other hand, the corresponding bipodal species [(≡SiO)2WO(CH2SiMe3)2] (2b) was obtained on SiO2–200 by release of both HCl and TMS. The formation of these species were demonstrated by mass balance analysis, elemental analysis, IR, advanced solid-state NMR (1D and 2D 1H, 13C, 29Si, and 17O), and EXAFS. Furthermore, DFT calculations allowed understanding and rationalizing the experimental results regarding grafting selectivity. Materials 2a and 2b proved to lead to stable and efficient supported tungsten oxo catalysts for propene metathesis under dynamic conditions at 80 °C. The symmetric bipodal precatalyst (expressed as [W(═E)(═CHR)(X)(Y)] (X = Y, E = spectator ligand)) showed somewhat higher activity than the asymmetric (X ≠ Y) counterparts.
Complete list of metadata

https://hal.insa-toulouse.fr/hal-01968826
Contributor : Insa Toulouse Scd <>
Submitted on : Thursday, January 3, 2019 - 12:17:10 PM
Last modification on : Wednesday, September 22, 2021 - 2:53:11 PM

Identifiers

Citation

D. Grekov, Y. Bouhoute, K. Szeto, N. Merle, A. de Mallmann, et al.. Silica-Supported Tungsten Neosilyl Oxo Precatalysts: Impact of the Podality on Activity and Stability in Olefin Metathesis. Organometallics, American Chemical Society, 2016, 35 (13), pp.2188-2196. ⟨10.1021/acs.organomet.6b00220⟩. ⟨hal-01968826⟩

Share

Metrics

Record views

185